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Presbyornis, Diatryma, and dromornithids (was Re: The duck that ruled the world)




Betty Cunningham wrote:

How would Diatryma be related to Bullockornis?

Interesting point. My guess is that they probably weren't closely related, since _Diatryma_ (a gastornithid, perhaps even the same as _Gastornis_) like brontornithids and phororhacids are usually thought to be related to modern Gruiformes (cranes, rails, coots).


I'm guessing there is a publication coming out on _Bullockornis_ and the affinities of the Dromornithidae.

While on the topic, can anyone tell me why "_Phorusrhacus_" is now the most common spelling for this genus? When I was a kid I distinctly remember it being spelled "_Phororhacus_".

How would Presbyornis be related to Bullockornis?

Again, probably not closely related. If _Presbyornis_ was a basal member of the Galloanserae (Galliformes+Anseriformes, or landfowl+waterfowl clade), and dromornithids evolved from such basal galloanserine stock, then this idea might fly. But...


Two papers published in 1997 poured cold water on the idea that _Presbyornis_ is a primitive or basal anseriform (Anseriformes = the duck-swan-goose-screamer group). Livezey (1997) and Ericson (1997), in two separate papers in the _Zoological Journal of the Linnaean Society_, both favour the idea that presbyornithids are the sister group to the modern Anatidae. This puts _Presbyornis_ phylogenetically closer to the anatids (modern ducks, geese and swans) than the anatids are to other extant anseriforms (screamers, magpie-goose). Livezey finds support for a Galliformes+Anseriformes clade, but Ericson does not.

I know Olson and Parris (1987), in their paper on New Jersey's Cretaceous birds, liked the idea that _Presbyornis_ was some type of missing link between the "transitional Charadriiformes" and the Anseriformes. This idea seems dead in the water (no pun intended).

Later (1995), Feduccia implicated these "transitional Charadriiformes" (to which most Late Cretaceous neognaths from North America have been referred) as important in the origin of all modern avian orders. This too cannot be supported by osteological evidence, and seems to be born entirely from Feduccia's "intuitive" notions regarding bird evolution. The "transitional Charadriiformes" are described by Livezey as an "undiagnosed, hypothetical group". He raises the interesting point that many poorly-known Cretaceous birds (_Telmatornis_, _Graculavus_, _Cimolopteryx_ etc come to mind) are assigned to modern bird orders in the same way that many Mesozoic mammals were once referred to the mammalian order Insectivora. They may not even be neornithines.

There's also some skepticism regarding the monophyly of the Charadriiformes, but that's another kettle of fish (Charadriiformes = "shorebirds" = auks, gulls, plovers etc).

Ahhh.  Time for a beer.


Tim

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